Hello, Here is a flower seen in Namibia during the rainy season, at Namutoni camp in Etosha national park it's trumpet-shaped and the plant grows quite high (1 meter for the one I have seen) Thank you for your help in this ID Cheers
Thank you Tony, So it's an invasive plant in Namibia. I hesitate now between Cryptostegia grandiflora and madagascariensis which look to me very similar